Yes... they are different things. If a flower of a Buttercup Squash is pollinated by another Buttercup Squash the fruit is a Buttercup Squash. If the same flower is pollinated by a Hubbard Squash (cross-pollination) then all bets on the make-up of the fruit are off.

Adopt the pace of nature, her secret is patience......Ralph Waldo Emmerson....

OK,the best way to explain this is ,cross-pollinated fruits will not change shape or taste until new fruit is grown from the seeds of the cross-pollinated fruit.So the fact is, plants growing from true buttercup squash seeds,whether they were cross pollinated or not will only produce buttercup squash from those plants.Even if the seeds from the cross pollinated squash are grown the next year,there is a "chance" that the squash will be different.